a. 1/3 AU b. 3 AU 5. Meteor showers occur

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1 1 AST104 Sp. 2006: WELCOME TO EXAM 3 Multiple Choice Questions: Mark the best answer choice on the answer form. Read all answer choices before making selection. CHECK YOUR WORK CAREFULLY BEFORE HANDING IN THE EXAM. 1. Which contains the most planets? a. our present solar system b. the Oort Cloud c. our Galaxy d. the Kirkwood gaps e. our solar nebula 2. If a star 10 light years away emits radio waves toward us on Earth then a. radio waves we receive are 10 years old. b. radio waves we receive are 1/10 year old. c. the star formed 4.6 billion years ago d. the star has a small magnetic field e. the Earth will disintegrate is a. 259 b c d e. none of the above 4. If light takes on average 8 minutes to reach the Earth from the sun, and light takes on average 24 minutes to reach an asteroid from the sun, what is the distance of this asteroid to the sun? a. 1/3 AU b. 3 AU c. 1/3 light years d. 30 light years e. 3 kilometers 5. Meteor showers occur a. at unpredictable intervals b. only about once every 10 years or so c. if Earth passes through the asteroid belt d. if Earth passes in the orbit of a comet e. only at the north and south pole 6. When is the sun lowest in the sky at noon in the northern hemisphere? a. winter solstice b. during a lunar eclipse c. summer solstice d. during a solar eclipse e. autumnal equinox 7. Which is true at vernal equinox? a. The duration of daylight and darkness are equal in the northern hemisphere but not in the southern hemisphere b. The duration of daylight and darkness are equal in the southern hemisphere but not in the northern hemisphere c. The duration of daylight and darkness are equal in both hemispheres d. autumn begins

2 2 e. summer begins 8. An observer on the Earth s south pole would always find a. The moon overhead at all times b. Darkness all year round. c. the celestial equator parallel to the horizon d. the celestial equator passing through the Zenith e. The sun overhead at all times 9. The sun and full moon have about the same angular size on the sky of 0.5 degrees. Why? a. the sun and moon are the same size and the same distance from Earth, but always in different parts of the sky. b. the moon is bigger than the sun and farther from Earth c. all spherical objects have the same angular size on the sky d. the moon is smaller than the sun, but closer to Earth e. none of the above 10. The measured densities of Jupiter and Uranus are nearly equal at about 1.3g/cm 3. This implies that Jupiter s is than that of Uranus. This further implies that Uranus has a higher mass fraction of rock and ice than Jupiter because are generally less dense than. a. uncompressed density; less; rocks+ices; gases+liquids b. uncompressed density; less; gases+liquids; rock+ice c. uncompressed density; more; rocks+ices; gases+liquids d. magnetic field; stronger; gases+liquids; rock+ice e. magnetic field; weaker; gases+liquids; rock+ice 11. The following are the apparent magnitudes of each of the 4 stars A,B,C,D: M A = 5, M B = 10, M C = 3, M D = 8. Which is the correct order of LEAST to MOST bright? a. D, C, A, B b. B, A, C, D c. A, B, C, D d. B, A, D, C e. D, B, C, A 12. You are dropped onto Earth at an unknown location and note that Polaris is 10 degrees above your northern horizon. What is your latitude? a. 80 degrees north b. 10 degrees north c. 10 degrees south d. 80 degrees south e. impossible to determine from only knowing this one angle 13. Total lunar eclipses occur at which moon phase? a. full b. new c. waxing crescent d. waning crescent

3 3 e. all of the above 14. Why are Uranus and Neptune blue? a. they have a surface covered in bluish rocks b. methane in their atmospheres absorbs primarily blue light c. methane in their atmospheres absorbs primarily red light d. hydrogen in their atmospheres absorbs primarily blue light e. hydrogen in their atmospheres absorbs primarily red light 15. Shepherd satellites play a key role in a. volcanos on Io b. narrowing planetary rings c. monitoring space weather d. forming the Earth e. providing data on distant planets 16. Which explains the extreme seasons on Uranus? a. its spin axis points nearly in the plane of its orbit b. it has a shorter orbital period than Earth c. it has a shorter orbital period than Jupiter d. its spin axis is tilted 23.5 degrees from the axis of its orbit e. it has the longest rotation period of any of the planets. 17. Which does NOT have planetary rings? a. Saturn b. Jupiter c. Uranus d. Neptune e. Mars 18. Which is farthest from the sun? a. Kuiper belt b. Oort cloud c. asteroid belt d. Neptune e. Jupiter 19. Light scattering by gas or dust plays a key role in explaining observations of a. a comet s dust tail b. the reddish color of a sunset c. the reddish glow of the moon in a total lunar eclipse d. the blue sky e. all of the above 20. An object in a circular orbit around the sun with a period of 8 years has a distance to the sun of a. 100 AU b. 8 AU c. 4 AU d. 2 AU e. 1/2 AU 21. An small object orbiting around the Earth in uniform circular motion has

4 4 a. zero acceleration b. a changing speed c. a changing velocity d. a speed that depends strongly on its mass e. a velocity that depends strongly on its mass 22. If the sun were four times more massive and twice as far from Earth as it is presently, then the gravitational force between the Sun and Earth would be a. 8 times weaker than it is now b. 8 times stronger than it is now c. 2 times weaker than it is now d. 2 times stronger than it is now e. the same as it is now 23. If an asteroid passes by Earth with a velocity equal to 10% of Earth s escape speed, the asteroid will soon follow a a. closed orbit b. open orbit c. hyperbolic orbit d. parabolic orbit e. impossible to determine without knowing the mass of the asteroid 24. A smart astronomer goes to the store to buy a telescope. Why does she demand a telescope with a large light collecting area? a. to see faint objects b. to resolve fine detail c. to magnify objects significantly d. a and b e. a,b and c 25. have wavelengths longer than visible light and travel at the speed of. a. radio waves, sound b. radio waves, light c. gamma-rays, light d. ultraviolet, light e. infra-red, heat 26. Why does a non-rotating star exhibit narrower spectral lines than a rotating star of identical spectral type? a. rotating stars emit only in the infra-red wavelength b. Doppler effect changes the line shape for the rotating star c. rotating stars are more massive and hotter than non-rotating stars d. rotating stars are less massive and cooler than non-rotating stars e. rotating stars have weaker magnetic fields 27. Which is NOT a characteristic of the Jovian planets compared to the terrestrial planets? a. lower average density b. larger mass c. liquid metallic hydrogen d. surface volcanism e. belts and zones 28. If a blackbody is cooled from a initial

5 5 temperature T I = 6000K down to a final temperature T F = 1500K, the ratio of wavelengths of maximum intensity λ I /λ F is a. 4 b. 1/4 c. 16 d. 1/16 e When occurs, an electron is sent to a higher energy level in an atom. When the electron falls back down, occurs. Neither is possible for a hydrogen gas. a. photon absorption, photon emission, fully ionized b. photon absorption, photon emission, partially ionized c. photon emission, photon absorption, fully ionized d. photon emission, photon absorption, partially ionized e. photon red shift, photon blue shift, fully ionized 30. Which of the following shows primarily an emission spectrum? a. the sun b. the moon c. a light bulb viewed through partially ionized hydrogen d. a light bulb not surrounded by gas e. a comet s gas tail 31. Which is true of a highly cratered surface? a. it must be on a moon and not a planet b. it is older than a region on the same object with less craters c. it is younger than a region on the same object with less craters d. it is formed by volcanism e. its host object has yet to go through the differentiation stage 32. Tidal effects can account for all of the following except a. volcanism on Io b. that the Moon always shows the same face to Earth c. why the 5 large satellites of Uranus keep their same faces toward Uranus d. Jupiter s red spot e. the high and low wave cycle on beaches 33. Which best describes why we do not see as prominent cloud layers on Uranus compared to Jupiter and Saturn? a. the atmosphere of Uranus contains little hydrogen, which is required for the clouds. b. Uranus outer atmosphere is too cold for these clouds to form c. The same clouds are there, but since we are farther away, the clouds are harder to resolve. d. Uranus rings block the clouds from our view e. Uranus rotates too slowly to produce such clouds. 34. Which most resembles the early

6 6 planetesimals formed in the solar nebula? a. Mars b. Earth c. Saturn d. Venus e. Asteroids 35. Which of the following is NOT true of our solar system? a. All of the planets orbit around the sun in the same direction. b. Currently active volcanos have been seen on more than one object. c. The larger planets formed in a cooler part of the solar nebula than the smallest planets. d. There is evidence that more than one planet or moon may have had liquid water. e. it is estimated to be slightly less than 5 million years old. 36. If two objects of the same density are formed at the same radius from the sun, which object is likely to remain geologically active longer? a. the smaller object b. the larger object c. the faster rotating object d. the slower rotating object e. the one with the stronger magnetic field 37. Which is a problem of refracting telescopes and a key reason reflecting telescopes are preferred for astronomical research? a. chromatic aberration b. poor magnification c. narrower range of accessible wavelengths d. all of the above e. none of the above 38. Einstein a. showed that Newton s theory must be corrected for weak gravity. b. showed that Newton s theory must be corrected for strong gravity. c. showed that gravity does not affect light d.showed that Newtonian gravity alone could not explain the orbit of Uranus e. b and c 39. Long period comets come from the a. Kuiper belt b. Kirkwood gaps c. Oort cloud d. supernovae e. inner regions of the solar nebula 40. When a meteorite impacts a planet, why is the crater impact so much larger than the object size? a. the impact induces nuclear fission upon impact which releases nuclear energy like a nuclear bomb b. the object impacts with a large kinetic energy that converts to heat upon impact which blows out a hole c. the object melts just before impact and the hot flowing liquid then spreads the impact

7 7 material over a larger area. d. all of the above e. none of the above True or False: 41. The nebula from which the sun and planets formed had a composition dominated by oxygen and nitrogen. 42. A blackbody of a given temperature emits electromagnetic radiation at more than one wavelength. 43. Knowing only (1) the speed of a satellite orbiting an unknown planet and (2) the distance of the satellite from that planet, we can directly obtain the numerical value of the planet s density. 44. The monthly phases of the moon are caused by Earth s shadow. 45. An observer standing in the path of totality during a solar eclipse is better able to see the solar corona than one outside the path of totality. 46. Aurorae are caused by meteor showers. 47. achondrites, stony-iron and iron meteorites likely come from differentiated asteroids. 48. Jupiter plays an important role in forming the Kirkwood gaps. 49. An object with a constant velocity is experiencing no acceleration. 50. Pluto is sometimes closer to the Sun than Neptune.

8 8 Answers 1.C 2.A 3.A 4.B 5.D 6.A 7.C 8.C 9.D 10.B 11.B 12.B 13.A 14.C 15.B 16.A 17.E 18.B 19. E 20. C 21. C 22. E 28. A 29. A 30. E 31. B 32. D 33. B 34. E 35. E 36. B 37. A 38. B 39. C 40. B 41. F 42. T 43. F 44. F 45. T 46. F 47. T 48. T 49. T 50. T 23. A 24. D 25. B 26. B 27. D